In order to generate a Landsat image, you will need to do the following:
Select a Scene (consists 4 quadrants: Q1-Q4) OR a Quad (one quater of a Scene).
Based on yor selection, you will then proceed to select a "Landsat Quad" or a
"Landsat Scene" from the respective pull-dowm menu.
Then, select a Sensor Combination, and if you want to zoom on the image or not. If so, select a zoom factor.
Finally, select Rows, and Columns to output, along with the (X,Y) Coordinate.
And click on "submit query" to get the image.